1. Field of the Invention
The present invention relates to an object detecting apparatus and method for detecting an object that combines the detection results of a radar means and an imaging means to detect an object.
2. Description of the Related Art
Driving support apparatuses such as collision-reduction apparatuses, adaptive cruise control apparatuses, and car-following apparatuses have been developed in recent years. In these driving support apparatuses, detection of a vehicle moving in front of the host vehicle is important. To improve detection accuracy, some object detection apparatuses have a radar means such as a millimeter wave radar and an imaging means such as a stereo camera. In an object detection apparatus having a radar means and an imaging means, the position (distance) of an object is detected by the radar means, and the size of the object is detected by the imaging means (refer to, for example, Japanese Patent Application Publication No. JP-A-2001-134769). In an object detection apparatus having a radar means and an imaging means, a radar-detected object detected based on radar information is compared with an imaging-detected object detected based on image information and a determination is made as to whether the radar-detected object and the imaging-detected object are the same. If it is determined that the objects are the same object, the object is set as a detected object (fusion object) such as a vehicle in front of the host vehicle (refer, for example, to Japanese Patent Application Publication No. JP-A-2004-117071).
When a new fusion object is set, a coincidence comparison is performed with the fusion object registered the previous time and, if there is coincidence, the fusion object information is updated. If, however, there is no coincidence, the new fusion object is newly registered, and the past fusion object that did not coincide is immediately deleted.
However, if the image obtained by the imaging means, such as a stereo camera or the like, is unstable, even if an object exists (and is detected by the radar), because of the influence by the condition of light reception (for example, at sunset or because of shadows), the imaging-detected object is often momentarily lost (undetected). Conventionally, when such momentary image loss occurs, the past object that did not coincide is immediately deleted and there is a repetition of the sequence of updating, deletion, updating, and so on of the fusion object, such that it is not possible to properly update the size of the object. Thus, there is a possibility that reliability of the information calculated using the history information (continuous detection rate) of the fusion object differs from the actual situation. Improper updating of the fusion object may also occur, for example when there is a momentary overlap between a leading vehicle and a white line on the road, or when there is a momentary overlap between two or more leading vehicles, so that the width of the imaging-detected object is erroneously detected as showing an extreme widening.